Tensioning device



Feb. 3, 1959 J. w, l. HIJNIS ETAL 2,872,128

TENSIONING DEVICE Filed sept. 7, 1955 INVENTOR ATTORNEY United States PatentO TENSIONING DEVICE James Watt Ijsbrand Heijnis and Jen Beyer, Arnhem, Netherlands, assignors to American Enka Corporation, Enka, N. C., a corporation of Delaware Application September 7 1955, Serial No. 532,920

'Claims priority, application Netherlands September 30, 1954 2 Claims. (Cl. 242-152) This invention relates to thread tensioning and more particularly to apparatus for imparting to a running thread or yarn a drag of magnitude that is adjustable through a very wide range.

ln arts of thread and yarn manipulation it is well known to impose tension or drag by pulling the yarn or thread through a tortuous passageway. This has been accomplished by the use of interdigitating bars and by the use of rollers so disposed as to form a tortuous thread path.

The disadvantage of interdigitating bars is the fact that they are stationary and hence cannot present the cumula tive resistance offered by both their surface `and their inertia. This lack of motion on the part of the thread contacting surface limits the scope of bar type tensioning devices to such simple, low demand installations as cone winders and the like.

The roller type tensioner is of wider capacity but, when used to produce high tensions, the compressive force between the rollers that define the drag path tends to cause thread breakage and wrap arounds which require stoppage of the machinery for their correction.

It is therefore an object of the present invention to provide an apparatus for thread or yarn tensioning that is characterized by reliable, trouble-free operation through a very wide range of adjustability.

Other objects and advantages of the present invention will be apparent from the following detailed discussion of several embodiments thereof in conjunction with the annexed drawings wherein:

Figure l is .a view in elevation of a thread tensioning device constructed in accordance with the teachings of the present invention;

Figure 2 is a view in elevation of a modified type of thread tensioning device according to the present invention; and

Figure 3 is a top plan View of a still further modification of the present invention.

Referring rst to Figure l, it is noted that there are shown two toothed wheels and 11 mounted on shafts 12 and 13 respectively. The teeth of the wheels 10 and 11 intermesh and the thread or yarn to be tensioned is drawn by any suitable draw-off device 14 through a path defined in part by these intermeshing teeth. Neither of the shafts 12 and 13 is driven and both are mounted for free rotation although a braking mechanism is associated with the shaft 12 as is indicated in broken lines in Figure l. This braking mechanism consists of a spring 15, a portion of the surface of which functionally bears on the shaft 12, and means such as a set screw to adjust the bias which it exerts against the shaft 12 and hence the braking effect which it exerts. The wheels 10 and 11 being mounted on freely rotatable shafts are not turned except by the action of the thread passing therebetween and the torque exerted by the thread is modified only by the brake 15. Under normal operating conditions the thread passing between the teeth of the wheels 10 and 11 assumes, at the point of maximum tooth engagement,

2,872,128 Patented Feb. 3, 19:59

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metry. In this way an increased tension is achieved which is superiorto the increase achievable by known devices. Although the wheels 10 and 11 are indicated as fixed to freely rotatable shafts it is apparent that, if desired, the shafts may be fixed and the wheels mounted for free rotation thereon. The brake mechanism 15 is, as shown, mechanical but a magnetic brake may be used. ln any case the brake per se forms no part of the present invention.

In the event that more tension is required than the arrangement of Figure 1 can provide, the arrangement shown in Figure 2 may be employed. In this case again there are two intermeshing toothed wheels 16 and 17 which intermesh in a zone indicated by the angle a. These intermeshing toothed wheels are mounted respectively on freely rotatable shafts 18 and 19. The shaft 18 may be braked by the same means as is applied to shaft 12 of Figure 1. The thread,.before being led between the intermeshing teeth is passed over a guide 20, and, after leaving the zone a representing the zone of interdigitation of the teeth, it passes through a zone extending for more than around the periphery of the toothed wheel 17 to a guide 21. The guide 21 maintains the thread issuing from between the two wheels in contact with the teeth of the wheel 17. A freely rotatable sheave or rotating guide may be used in the case of both guides 20 and 21. The effect of the wrap of the thread around the toothed wheel 17 through the angle is greatly to increase the amount of drag that may be imposed as between the arrangements of Figure 1 and Figure 2. For example, with the arrangement of Figure 2 it is possible to have an entering thread tension of about 2 grams and a tension near the guide wheel 21 of about 600 grams representing an increase by a factor of 300.

Instead of having the guide 21 in the form of a freely rotatable roller, any other form of guide may be used although a freely rotatable wheel has been found to be preferred for untwisted threads. Itis possible so to position the guide 20 that the thread somewhat wraps the wheel 16 before it enters the zone of interdigitation. This is shown in broken lines in Figure 2. It can be seen that the effects of the peripheral wrap of the yarn or thread around the wheel 17 is to bias the wheel in a clockwise direction as it is shown in Figure 2. This causes increased pressure on the teeth of the wheel 16 and hence increased drag on the yarn. The angle may be of any size although it has been found to be most effective when it exceeds 180.

The arrangement of Figure 3 can be used to produce a tension increase of 200 times with untwisted threads. In Figure 3 the toothed wheels between which the thread runs bear numerals 22 and 23. The wheel 22 is keyed on a shaft 24 which also carries keyed thereto a toothed wheel 25 located at a point axially spaced from the wheel 22. The toothed wheel 25 meshes with a similar wheel 26 which is mounted for free rotation on the shaft 27 which carries the wheel 23 keyed thereon. A brake mechanism 28 as shown in Figures l and 2 acts upon the shaft 24. The wheels 23 and 26 are connected by a slightly tensioned spring 29 coaxially surrounding the shaft 27 and exerting light torque on the wheel 23 causing the wheel 23 not only to be subjected to the force exerted by the thread but also to the force pressing the teeth toward one another as in Figure 2 but caused by the spring rather than the wrap.

Figure 3 represents a preferred embodiment of the present invention because during normal operation the leading tooth faces of the wheel 23 and the following tooth faces of the wheel 22 are pressed together with a force threadisdrawn'upwardly between the'tyheels 22Y and'23' by such adevice, not4 shown. Surprisingly, ithas been found that the device according tothe invention may be` applied-'with particularly good results for'tensioning an untwisted articial thread orlike'yarn composed'of continuous l'aments. It has been found that in this case it is possibleto producevery high tensions inthe thread or yarn-ewhileavoiding filament rupture; There are, therefore, no wraps at all and,v besides, the quality of threads and' yarns thus tensioned is'superior tothat -of threads or yarns-tensioned'by' means of the known devices, due to thev absence of- -brokenfilaments.

It is important to note that While the resistance to rotation of thevarious wheelsshown in the Ydrawings is adjustable insomedegree,A the spacing'between'the teeth is Xed-for any installation and in no sense are the wheels urged toward' one another to vary thepressure exerted on theyarn.

It is possible that the iilaments are not ruptured due to the fact thatv inpassing through the toothed Wheels the opposite sides of the thread come alternately into contact with the teeth of the wheels thus allowing the filaments to spread and all of them to come underapproximately the same tension.

Although thedevice accordingto the invention may be used anywhere where it is necessary to tension twisted or luntwistedethreads; thel device'is partieularlysuitable, in

view of its relatively small dimensions and its exceedingly high braking power, to be applied in twisting devices, for example in those of the type described in the Belgian patent speciiication 523,245.

What is claimed is:

l. Yarn-tensioning apparatus comprising a pair of toothed: wheelsY mounted in xed spacial relationship for rotation in-mesh, means to draw a yarnthrough the meshing teeth of said Wheels to-impart' torque to said Wheels to cause them to rotate, braking means to retard the rotation of one of said wheels, and means resiliently to apply a torque tothe other of said wheels.

2. Yarn-tensioning apparatus comprising a pair of toothed wheels mounted in fixed spacial relationship for rotation in mesh, means to draw a yarn through the meshing teeth of said wheels to impart torque to said Wheels to cause them to rotate, braking means to retard the rotation of one of said wheels, a freely rotatable gear, a gear iixedV to rotate with the brake wheel, said gears being in mesh, and. coil spring means interconnecting said freely rotatable gear and said unbraked wheel.

Praska Mar. l, 1910 Allen e Aug. 10, 1915 

